A RESPIRATION CALORIMETER. 



copper wall. The length of the wooden cylinder and of the wires is 

 such that when one end is thus inserted in the thimble the junctions at 

 the other end are exactly in the plane of the zinc wall. The element 

 is held in place by a cork firmly inserted in the outer aperture of the 

 ring in the zinc wall. The ends of the two long German-silver wires 

 that lead to the junctions are passed through holes in the cork, which 

 are far enough apart to insure insulation between the two German- 

 silver wires, and likewise far enough from the edge of the cork to in- 

 sure insulation between these wires and the copper ring soldered into 

 the zinc wall. The ends of the thermal junctions are far enough below 



Fig. 26. 



Fig. 27. 



Fig. 28. 



FIG. 26. Thermo-Electric Element. Iron wires (represented by black line) and German-silver 

 wires are soldered with silver solder, making a series of four junctions at each end. 



FIG. 27. Thermo-Electric Element Mounted on Wooden Rod. The iron and German-silver wires 

 are pressed well into slits in the sides. The two projecting wires are for connections. 



FIG. 28. Method of Installing the Thermo-Electric Elements in the Metal Walls. A short tube 

 soldered in the zinc wall holds the element in place. 



the outer surface of the wooden cylinder to prevent any possible elec- 

 trical contact with either the copper thimble on the copper wall or the 

 ring on the zinc wall, while the small air-gap does not seem to retard 

 unduly the passage of heat from the copper or zinc wall to the junc- 

 tions. In this position a junction is able to take up rapidly at each 

 end the temperature of the corresponding metal wall. 



The detection of differences in temperature between the two metal 

 walls by means of the thermal junctions thus inserted depends upon 

 the fact that if the ends of the two kinds of wire forming the junction 

 are unequally heated a current of electricity is developed, the intensity of 



